LUIT

NAME

luit −
Locale and ISO 2022 support for Unicode terminals

SYNOPSIS

luit [
options ] [ −− ] [ program
[ args ] ]

DESCRIPTION

Luit is
a filter that can be run between an arbitrary application
and a UTF-8 terminal emulator. It will convert application
output from the locale’s encoding into UTF-8, and
convert terminal input from UTF-8 into the locale’s
encoding.

An application
may also request switching to a different output encoding
using ISO 2022 and ISO 6429 escape sequences. Use
of this feature is discouraged: multilingual applications
should be modified to directly generate UTF-8 instead.

Luit is
usually invoked transparently by the terminal emulator. For
information about running luit from the command line,
see EXAMPLES below.

OPTIONS

−h

Display some summary help and
quit.

−list

List the supported charsets and encodings, then
quit.

−V

Print luit’s version and quit.

−v

Be verbose.

−c

Function as a simple converter from standard input to
standard output.

−p

In startup, establish a handshake between parent and
child processes. This is needed for some systems, e.g.,
FreeBSD.

−x

Exit as soon as the child dies. This may cause
luit to lose data at the end of the child’s
output.

−argv0name

Set the child’s name (as
passed in argv[0]).

−encodingencoding

Set up luit to use
encoding rather than the current locale’s
encoding.

+oss

Disable interpretation of single shifts in application
output.

+ols

Disable interpretation of locking shifts in application
output.

+osl

Disable interpretation of character set selection
sequences in application output.

+ot

Disable interpretation of all sequences and pass all
sequences in application output to the terminal unchanged.
This may lead to interesting results.

−k7

Generate seven-bit characters for keyboard input.

+kss

Disable generation of single-shifts for keyboard
input.

+kssgr

Use GL codes after a single shift for keyboard input. By
default, GR codes are generated after a single shift when
generating eight-bit keyboard input.

−kls

Generate locking shifts (SO/SI) for keyboard input.

−glgn

Set the initial assignment of GL. The argument should be
one of g0, g1, g2 or g3. The
default depends on the locale, but is usually g0.

−grgk

Set the initial assignment of GR. The default depends on
the locale, and is usually g2 except for EUC locales,
where it is g1.

−g0charset

Set the charset initially
selected in G0. The default depends on the locale, but is
usually ASCII.

−g1charset

Set the charset initially
selected in G1. The default depends on the locale.

−g2charset

Set the charset initially
selected in G2. The default depends on the locale.

−g3charset

Set the charset initially
selected in G3. The default depends on the locale.

−ilogfilename

Log into filename all
the bytes received from the child.

−ologfilename

Log into filename all
the bytes sent to the terminal emulator.

−aliasfilename

the locale alias file
(default:
/usr/share/X11/locale/locale.alias).

−−

End of options.

EXAMPLES

The most
typical use of luit is to adapt an instance of
XTerm to the locale’s encoding. Current
versions of XTerm invoke luit automatically
when it is needed. If you are using an older release of
XTerm, or a different terminal emulator, you may
invoke luit manually:

$ xterm
−u8 −e luit

If you are
running in a UTF-8 locale but need to access a remote
machine that doesn’t support UTF-8, luit can
adapt the remote output to your terminal:

$ LC_ALL=fr_FR
luit ssh legacy-machine

Luit is
also useful with applications that hard-wire an encoding
that is different from the one normally used on the system
or want to use legacy escape sequences for multilingual
output. In particular, versions of Emacs that do not
speak UTF-8 well can use luit for multilingual
output:

$ luit
-encoding ’ISO 8859-1’ emacs -nw

And then, in
Emacs,

M-x
set-terminal-coding-system RET iso-2022-8bit-ss2 RET

FILES

/usr/share/X11/locale/locale.alias

The file mapping locales to
locale encodings.

SECURITY

On systems with
SVR4 (“Unix-98”) ptys (Linux version 2.2 and
later, SVR4), luit should be run as the invoking
user.

On systems
without SVR4 (“Unix-98”) ptys (notably BSD
variants), running luit as an ordinary user will
leave the tty world-writable; this is a security hole, and
luit will generate a warning (but still accept to run). A
possible solution is to make luit suid root;
luit should drop privileges sufficiently early to
make this safe. However, the startup code has not been
exhaustively audited, and the author takes no responsibility
for any resulting security issues.

Luit
will refuse to run if it is installed setuid and cannot
safely drop privileges.

BUGS

None of this
complexity should be necessary. Stateless UTF-8 throughout
the system is the way to go.

Charsets with a
non-trivial intermediary byte are not yet supported.

Selecting
alternate sets of control characters is not supported and
will never be.

SEE ALSO

AUTHOR

The version of
Luit included in this X.Org Foundation release was
originally written by Juliusz Chroboczek
<jch@freedesktop.org> for the XFree86 Project and
includes additional contributions from Thomas E. Dickey
required for newer releases of xterm(1).